An average human adult requires about 2000-2500 Kcal/day. If the average human burns about the same amount per day, a net balance is generally maintained and the person's weight should remain steady. However, many people consume more calories than they burn. This can lead to obesity, a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to a reduced life expectancy and/or increased health problems, such as heart disease, type 2 diabetes, sleep issues, and cancer. A person can be considered obese if the person's body mass index (BMI; a measure of body fat based on height and weight) is greater than 30 kg/m2.
The current epidemic of obesity and its numerous complications have resulted in enormous economic and healthcare burdens. Treatments for obesity often include dieting and/or increasing physical exercise, but such conventional therapies can be ineffective and/or difficult to comply with. Anti-obesity drugs also can be taken to reduce appetite or inhibit fat absorption, and in severe cases, surgery can be performed. Weight loss supplements and surgery have their own complications, however.